1. Field of the Invention
This invention relates to a disposable blood collection tube holder having particular application to the field of vacuum tube phlebotomy and means by which to safely and reliably shield an associated hypodermic needle cannula after use so as to prevent both an accidental needle stick and the possible splattering of a disease laden blood sample as a consequence of cannula whiplash.
2. Prior Art
The heightened awareness of the need for infection control, while drawing samples from blood-precautionary patients, has inspired the design of many safety blood collection tube holders which employ a needle shielding means so as to reduce the probability of an accidental needle stick by a contaminated needle cannula and by nosocomial infection of lethal viruses and other microorganisms. By way of example, devices are known which include a sliding outer protective sleeve which is advanceable axially over an inner cylinder to surround and shield a contaminated hypodermic needle, after use. However, a problem commonly suffered by these conventional devices is their tendancy to splatter microdroplets of a patient's blood, both inside and outside of the outer sleeve, when said outer sleeve is advanced to and locked in its forward-most shielding position.
More particularly, every needle cannula has its own characteristic frequency response by which it may be susceptable to whiplash through either sympathetic vibration or imposed impact loads. Such vibrations and loads are frequently generated by the jarring impact forces associated with advancing and locking the outer sleeve in its forward-most position relative to the inner cylinder. As a consequence of these impact locking forces and the corresponding needle whiplash, the possibility of splattering a disease laden blood sample still exists, even though the cannula is completely surrounded and shielded.
An example of a shielded blood collection tube holder to which the present invention is applicable may be found by referring to U.S. Pat. No. 4,758,231 issued July 19, 1988, which patent has been assigned to the assignee of this patent application.